We have a lot of firepower up front, so I'd probably go with the 4-4-2 diamond, because it would be a bit of a waste to only play one striker, because we've got three who are very good:
GK - De Gea -
Awesome keeper, so no question.
RB - Rafael - only natural right back in our team and missed when he's not there. Injury prone though.
CB - Phil Jones - either him Blackett or McNair. Good to see them get chances at least.
CB - Marcos Rojo - can play there, but why buy someone and play them out of position. MAYBE Evans ?
LB - Luke Shaw - or Marcos Rojo, since he is naturally a left back and more experienced at the top level.
DMF - Daley Blind - one of his more natural positions, just not a physical presence.
CMF (right) - Ander Herrera - creative and likes a tackle too.
AMF - Rooney - we'll play two up front, so he will link up well with them and he tracks back.
CMF (left) - Di Maria - good in the diamond and a proven world class player. No question really.
CF - Falcao - has to start when fully fit.
CF - Van Persie - should link up well with Falcao when on form. Rooney instead when not on form.
Not 100% sure on the starting eleven up above due to the players we have, but we do have a much improved squad and different players will play different oppositions.
We've got a lot of talented attacking players, but only one truly awesome winger, in Di Maria.
Juan Mata would start, but he doesn't track back and I do think we need to be good at counterattacking and need pacey players for that and he doesn't fit that category, so I think he'll have to drop to the bench.
If Falcao, Rooney and Van Persie are all fit and on form, then all have to start, because they are all world class on form and can fit in the diamond and we'll probably play that.
Falcao would obviously be on of the centre forwards.
Van Persie would be too and I do think he will link up with Falcao, though age might be an issue and it will depend on his form.
Rooney can play as an attacking midfielder and would probably play that role in the diamond, as he tracks
backs and can be creative. Fellaini could maybe play here at times.
Di Maria will probably start as a left central midfielder in the diamond and that is perfectly fine.
As for the right side of central midfield, there are two main options - Ander Herrera or Fellaini ? Ander Herrera will offer creativity and is more of a technical player and Fellaini will offer more of a physical presence. Whoever starts will probably depend on the opposition we're playing. Its disappointing to drop a player who is in form. Good options to have. Maybe either one can maybe play as a defensive midfielder, though you'd rather play players in there best position. Carrick could either play there or as a defensive midfielder, though I'd prefer him here.
Daley Blind should probably play as a defensive midfielder, as its more of a natural position for him. If we get a squad the way I prefer it (my system too), I'd like Phil Jones to compete with Daley Blind for defensive midfield, because Phil Jones likes to make tackles and has done well in midfielder before. He's not a ball player though, which is a shame and would be even better. For though, I'd use him as a centre back, because he's one of our more experienced one. Some centre backs might need to leave though.
We'll have a lot of options when everyone is fit and some can play in more than one position, so it will be interesting how our line up will generally look and we'll most likely play the same starting eleven if they do well.
There are many options and I do think we can do well if we use our players properly.
It will be interesting who goes and who comes in, in January and the summer, if we get anyone there.
Once again, its going to be very hard to decide who to start when everyone is fully fit.